Pump device

ABSTRACT

A pump device is configured so that a first drive shaft  20  for driving a first pump element E 1  and a second drive shaft  40  for driving a second pump element E 2  are connected through a third drive shaft  50 , and a first joint  51  and a second joint  52  are respectively connected between the first drive shaft  20  and the third drive shaft  50 , and between the second drive shaft  40  and the third drive shaft  50 , each of the first joint and the second joint being configured to permit a joining angle change or a change in an amount of eccentricity between the corresponding drive shafts. As a result of this configuration, a flexural deformation produced in the first and second drive shafts  20, 40  can be absorbed by means of the first and second joints  51, 52 , and thus it is possible to suppress the problem of the flexural deformation of one of the first and second drive shafts  20, 40  affecting the other.

TECHNICAL FIELD

The present invention relates to a pump device in which a plurality of pumps are connected in series to each other.

BACKGROUND ART

As a prior art pump device, for instance, a pump device as disclosed in the following Patent document 1 is known.

In the prior-art pump device, a drive shaft of a first pump and a drive shaft of a second pump are connected to each other via a specified coupling structure. Also provided on the outer periphery of the drive shaft of the first pump is a seal member for suppressing an inflow of fluid from the second pump side into the first pump side.

CITATION LIST Patent Literature

Patent document 1: JP2005-330969 A

SUMMARY OF INVENTION Technical Problem

However, according to the prior-art pump device, when an uneven internal pressure in one of these two pumps has occurred, the whole of the drive shafts connected to each other is brought into an eccentric state with a flexural deformation from the high-pressure (discharge pressure) side to the low-pressure (suction pressure) side due to the uneven internal pressure. As a result, an undesired clearance gap (a radial clearance) is formed or produced between the drive shaft and the associated seal member. Thus, there is a possibility of an undesirable inflow (mixing) of fluid pertaining to the one pump from the one pump side into the other pump side by way of the undesired clearance gap.

It is, therefore, in view of the previously-described drawbacks of the prior-art pump device, an object of the invention to provide a pump device capable of suppressing the problem that a flexural deformation of a drive shaft associated with one pump element extends to a drive shaft associated with the other pump element.

Solution to Problem

The invention is characterized in that, specifically, a first drive shaft provided for driving a first pump element and a second drive shaft provided for driving a second pump element are connected through a third drive shaft, and a first joint and a second joint are respectively connected between the first drive shaft and the third drive shaft, and between the second drive shaft and the third drive shaft, each of the first and second joints being configured to permit a joining angle change or a change in an amount of eccentricity between the corresponding drive shafts.

In this manner, the first drive shaft and the second drive shaft are connected through the third drive shaft. In connecting among them, the first joint and the second joint are respectively connected between the corresponding drive shafts (between the first and third drive shafts, and between the second and third drive shafts), so as to permit a joining angle change or a change in an amount of eccentricity between the corresponding drive shafts. As a result of this configuration it is possible to suppress the problem of a flexural deformation of one of the first and second drive shafts affecting the other.

According to another aspect of the invention, a first drive shaft provided for driving a first pump element that constructs a variable displacement vane pump and a second drive shaft provided for driving a second pump element are connected through a joint, and a bearing is provided between the joint pertaining to the second drive shaft and the second pump element, and also a pair of seal members are provided between the bearing and the second pump element.

That is to say, the first pump element, which is an unbalanced pump, is easy to produce a flexural deformation, but the bearing and the seal members are provided on the second drive shaft side. Thus, it is possible to suppress the flexural deformation of the first drive shaft from affecting the seal members.

Advantageous Effects of Invention

According to the invention, it is possible to suppress the problem of a flexural deformation of one of a first drive shaft and a second drive shaft affecting the other.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal cross-sectional view illustrating a pump device according to a first embodiment of the invention.

FIG. 2 is a cross-sectional view taken along the line X-X of FIG. 1.

FIG. 3 is a disassembled perspective view illustrating a second pump element shown in FIG. 1.

FIG. 4 is a longitudinal cross-sectional view illustrating a pump device according to a second embodiment of the invention.

FIG. 5 is a longitudinal cross-sectional view illustrating a pump device according to a third embodiment of the invention.

FIG. 6 is a longitudinal cross-sectional view illustrating a pump device according to a fourth embodiment of the invention.

FIG. 7 is a longitudinal cross-sectional view illustrating a pump device according to a fifth embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

Embodiments of a pump device according to the invention are hereinafter described in detail with reference to the drawings. In the respective embodiments hereunder described, the invention is exemplified in a pump device in which a variable displacement vane pump serving as a fluid pressure source for an automotive power steering device and a fuel pump are integrally constructed. In the following description, the left-hand side in FIG. 1 (i.e., the side of a first pump element E1) is defined as “front”, whereas the right-hand side in FIG. 1 (i.e., the side of a second pump element E2) is defined as “rear”. Additionally, the direction of the axis of each of drive shafts is referred to simply as “axial direction”, whereas the direction perpendicular to the “axial direction” is referred to as “radial direction”.

First Embodiment

FIGS. 1-3 show the first embodiment of a pump device according to the invention. As shown in FIG. 1, the pump device 1 is mainly constructed by a pump housing 10 having a first pump element housing part 11 a and a second pump element housing part 12 a formed therein, a first pump element E1 housed in the first pump element housing part 11 a, a first drive shaft 20 for driving the first pump element E1, a second pump element E2 housed in the second pump element housing part 12 a, a second drive shaft 40 for driving the second pump element E2, and a third drive shaft 50 housed in the pump housing 10 and provided for connecting the first drive shaft 20 and the second drive shaft 40.

The above-mentioned pump housing 10 is structured to be split into three sections along the respective axial directions of the first, second, and third drive shafts 20, 40, and 50. The pump housing is formed of a first pump housing 11 having the first pump element housing part 11 a for housing therein the first pump element E1, a second pump housing 12 having the second pump element housing part 12 a for housing therein the second pump element E2, and a third pump housing 13 interposed between the first pump element housing part 11 a and the second pump element housing part 12 a for housing the third drive shaft 50. Also, the pump housing is configured such that these three pump housings are connected in series to each other along the respective axial directions of the first, second, and third drive shafts 20, 40, and 50.

The first pump housing 11 is formed into a substantially bottomed cylindrical shape and configured to surround the outer periphery of the first drive shaft 20. The first pump housing has a cylindrical section 11 b formed on its inner peripheral side so as to form the first pump element housing part 11 a and a bottom section 11 c provided on one axial end side of the cylindrical section 11 b (on the side being opposite to the second drive shaft 40) so as to form a front end wall of the first pump element housing part 11 a.

A shaft insertion hole 14, into which the first drive shaft 20 is inserted, is formed through a central portion of the bottom section 11 c along the axial direction. The front end portion of the first drive shaft 20, which faces to the outside through the shaft insertion hole 14, is linked through a gear (not shown) to an engine (not shown) for receiving or inputting a driving force from the engine.

Also, the shaft insertion hole 14 is formed into a stepped shape, diametrically-enlarged toward the front end side. The front end of the first drive shaft 20 is supported by means of a bearing B3 accommodated and held in a front-end side large-diameter portion 14 a and a bearing B4 accommodated and held in a rear-end side small-diameter portion 14 b. Hereupon, the bearing B3 is constructed by a generally-known ball bearing, whereas the bearing B4 is constructed by a generally-known plane bearing. The bearing B4 is lubricated by working fluid flowing out of the side of the first pump element E1.

A seal member S0, which is a generally-known seal member, is accommodated and held in a middle-diameter portion 14 c formed between the large-diameter portion 14 a and the small-diameter portion 14 b. An outflow of working fluid flowing out of the side of the first pump element E1, which provides lubrication for the bearing B4, can be suppressed by means of the seal member S0.

As shown in FIGS. 1 and 2, the first pump element E1 is provided with an annular adapter ring 23, an annular cam ring 24, a rotor 21, and rectangular plate-shaped vanes 22. Adapter ring 23 is fitted to the inner peripheral wall of the first pump element housing part 11 a. Cam ring 24 is accommodated on the inner peripheral side of adapter ring 23 such that the annular cam ring can be displaced eccentrically to the axis Q of the first drive shaft 20 (i.e., the rotation center of rotor 21 described later). Rotor 21 is rotatably accommodated and located on the inner peripheral side of cam ring 24 and driven by the first drive shaft 20. Vanes 22 are retractably accommodated and held in a plurality of slots recessed or cut in the outer periphery of rotor 21 along the radial direction. The vanes are brought into sliding-contact with the inner peripheral surface of cam ring 24 while flying out radially outward during rotation of the rotor 21, so as to define a plurality of pump chambers Px in an internal space formed between the cam ring 24 and the rotor 21.

Adapter ring 23 is provided with a pin 25 a retained in a circular-arc shaped groove formed at the upper end of its inner peripheral surface, and serving as a whirl-stop pin for the cam ring 24. Also provided is a plate member 25 b held in a rectangular groove formed in the inner peripheral surface and located adjacent to the left-hand side of the circular-arc shaped groove, viewing in FIG. 2, and serving as a support for supporting rocking motion of cam ring 24. The plate member 25 b is retained in the rectangular groove over its entire axial width. Also provided is an axially-extending seal member provided in the inner peripheral surface of adapter ring 23 on the side substantially diametrically opposed to the plate member 25 b. By virtue of the seal member and plate member 25 b, a first fluid-pressure chamber P1 and a second fluid-pressure chamber P2 are defined between the adapter ring 23 and the cam ring 24 in the radial direction, for the purpose of rocking-motion control for the cam ring 24.

Cam ring 24 is supported on the plate member 25 b and configured to be rockably displaced toward either of the side of the first fluid-pressure chamber P1 and the side of the second fluid-pressure chamber P2, while rolling on the plate member 25 b. Also, cam ring 24 has an engagement groove cut in its outer periphery and having a substantially semi-circular shape in cross section. Fitted-engagement of the semi-circular engagement groove with the pin 25 a enables the previously-discussed whirl-stop.

The first pump element E1 is held by a substantially disk-shaped pressure plate 26 a and a side plate 26 b, while being sandwiched between them. The pressure plate 26 a is located on the rear end side of the first pump element housing part 11 a and arranged adjacent to the front end side of the third pump housing 13. With this configuration, a plurality of pump chambers Px are defined between the cam ring 24 and the rotor 21 in the radial direction by means of the vane pairs, each pair being comprised of two adjacent vanes 22, 22, the pressure plate 26 a, and the side plate 26 b. The volume of each of the pump chambers Px can be increased or decreased by rocking motion of cam ring 24 in a left-to-right direction in FIG. 2, thereby varying an inherent discharge flow rate.

A coil spring 27 is provided in the second fluid-pressure chamber P2. The coil spring is supported by a retainer, which is screwed into one side of the first pump housing 11. With the coil spring 27 pre-loaded by the retainer, the cam ring 24 is constantly biased toward the side of the first fluid-pressure chamber P1, that is, in a spring-loaded direction such that the amount of eccentricity of the cam ring with respect to the rotation center Q of rotor 21 (hereinafter referred to simply as “eccentricity”) becomes maximum.

Also, the pressure plate 26 a of the rear end side of the first pump element housing part 11 a has a substantially crescent-shaped suction port 28 a indicated by a virtual line (a broken line) in FIG. 2 and formed and cut along the circumferential direction in a prescribed region (hereinafter referred to as “suction region”) in which the internal volume of each of the pump chambers Px gradually increases with rotation of rotor 21. The suction port 28 a is connected to a suction passage 28 b located at the lower end of the third housing 13 and formed into a substantially L shape in longitudinal cross section. Hence, working fluid, which is introduced from the outside (a reservoir tank not shown) through the suction passage 28 b, is delivered into each pump chamber Px positioned in the previously-discussed suction region.

On the other hand, the upper half of the pressure plate 26 a of the rear end side of the first pump element housing part 11 a and the upper half of the side plate 26 b of the front end side of the first pump element housing part 11 a have substantially crescent-shaped discharge ports 29 a respectively indicated by a virtual line (a broken line) in FIG. 2 and formed and cut along the circumferential direction in a prescribed region (hereinafter referred to as “discharge region”) in which the internal volume of each of the pump chambers Px gradually decreases with rotation of rotor 21. These discharge ports 29 a are located above the suction port 28 a in the vertical direction in a vehicle-mounted state, and connected to a discharge passage 29 b formed in the first pump housing 11. Hence, working fluid, which is pressurized in each pump chamber Px positioned in the previously-discussed discharge region, is discharged through the discharge passage 29 b to an external device (a power steering device PS).

By the way, as shown in FIG. 2, the downstream side of discharge passage 29 b bifurcately branches into two branch passages. Part of discharge oil (working fluid) is introduced through one of the branch passages, namely, a first discharge passage 29 c into a first pressure chamber 33 (described later) of a control valve 30, whereas part of discharge oil is introduced through the other of the branch passages, namely, a second discharge passage 29 d into an external device (power steering device PS). In FIG. 2, reference sign 35 denotes a metering orifice that produces a fore-and-aft differential pressure, by which the control valve 30 is operated for the purpose of discharge pressure control (discharge flow rate control).

Regarding the control valve 30, a valve element 32 is slidably installed in a valve bore 31 formed inside of the lower end of the first pump housing 11, and thus an internal space of valve bore 31 is partitioned into the left-hand side first pressure chamber 33 and the right-hand side second pressure chamber 34 (see FIG. 2). Fluid pressure on the upstream side of metering orifice 35 is introduced into the first pressure chamber 33 by way of the first discharge passage 29 c, whereas fluid pressure on the downstream side of metering orifice 35 is introduced into the second pressure chamber 34 through a pilot orifice 39 by way of the second discharge passage 29 d.

With the previously-discussed configuration, when the valve element 32 is positioned on the left-hand side (viewing FIG. 2), a low pressure, which is a suction pressure, is introduced through a communication passage 36 into the first fluid-pressure chamber P1, and thus cam ring 24 is held at its maximum eccentric state by a biasing force of coil spring 27. Conversely when the valve element 32 is positioned on the right-hand side (viewing FIG. 2), the discharge pressure adjusted by the control valve 30, that is, the regulated pressure within the control valve 30 is introduced into the first fluid-pressure chamber P1. Thus, cam ring 24 is pushed by a biasing force produced based on the internal pressure in the first fluid-pressure chamber P1, so as to move in a direction such that the eccentricity decreases.

Also, a relief valve 37 is provided and located in the valve element 32 and configured to face the second pressure chamber 34, for relieving the fluid pressure in the second pressure chamber 34. The downstream side of relief valve 37 is configured to communicate with the suction side by way of a communication passage 38. When the fluid pressure in the second pressure chamber 34 reaches a pressure value greater than or equal to a specified pressure, that is, when the pressure of the load side (the side of power steering device PS as discussed previously) reaches a high enough value greater than or equal to the specified pressure, the relief valve opens and thus the pilot orifice 39 produces a pressure difference. Accordingly, the valve element 32 moves toward the right-hand side, thereby reducing the discharge flow rate. That is to say, the relief valve has a pilot-relief function in conjunction with the pilot orifice.

As shown in FIGS. 1 and 3, the second pump housing 12 is formed into a bottomed cylindrical shape and has a two-split structure in which the second pump housing is split into two sections along the axial direction of the second drive shaft 40. Concretely, the second pump housing is comprised of a substantially cylindrical pump body 15 configured to surround the outer periphery of the second drive shaft 40 and define the second pump element housing part 12 a inside of the pump body, and a cover member 16 located at the rear end of the pump body 15 and making up the rear end wall of the second pump element housing part 12 a.

A shaft insertion hole 15 b, into which the second drive shaft 40 is inserted, is formed through the bottom 15 a of pump body 15 that closes the front end of the second pump element housing part 12 a. The front end portion of the second drive shaft 40, which faces to the outside through the shaft insertion hole 15 b, is connected through the third drive shaft 50 to the first drive shaft 20. Hereby, the driving force of the engine (not shown) is inputted from the first drive shaft 20 through the third drive shaft 50 to the second drive shaft 40. On the other hand, the cover member 16 is formed into a substantially plate shape. The cover member 16 and the pump body 15 are fastened together with a plurality of bolts T1 and fixedly connected to the third pump housing 13.

The second pump element E2 is constructed by a drive gear 41 and a driven gear 42. The drive gear 41 is installed on the outer periphery of the second drive shaft 40 for co-rotation with the second drive shaft 40, and has a plurality of teeth 41 a formed on its outer periphery. The driven gear 42 is installed on the outer periphery of a driven shaft 43 arranged parallel to the second drive shaft 40 for co-rotation with the driven shaft 43, and has a plurality of teeth 42 a formed on its outer periphery and brought into meshed-engagement with the drive gear 41. These gears 41, 42 are both accommodated in the second pump element housing part 12 a.

By the way, the front end side of the second drive shaft 40 is supported through a bearing B5, which is accommodated and held in an axial intermediate portion of the shaft insertion hole 15 b of pump body 15, while the rear end side of the second drive shaft 40 is supported through a bearing B6, which is accommodated and held in a bearing bore portion 16 a recessed in the cover member 16. Hereupon, each of the bearings B5, B6 is constructed by a generally-known needle bearing. These bearings are lubricated by fuel flowing out of the side of the second pump element E2. On the other hand, regarding the driven shaft 43, in a similar manner to the second drive shaft 40, the front end side of the driven shaft is supported through a bearing B7, which is accommodated in the bottom 15 a of pump body 15, while the rear end side of the driven shaft is supported through a bearing B8, which is accommodated in the cover member 16.

Also, a pair of ports, that is, a suction port 17 a and a discharge port 18 a are formed to open at the lower end of pump body 15 and configured to communicate with the second pump element housing part 12 a. Concretely, the suction port 17 a is provided to open onto one side of pump body 15 in its width direction, while the discharge port 18 a is provided to open onto the other side of pump body 15 in the width direction. The suction port 17 a is communicated with one side of the previously-discussed two gears 41, 42 by way of an internal suction passage 17 b, while the discharge port 18 a is communicated with the other side of two gears 41, 42 by way of an internal discharge passage 18 b.

As shown in FIG. 1, the third pump housing 13 is formed into a substantially cylindrical shape. The third pump housing 13 is fixedly connected to the first pump housing 11 via a plurality of bolts T2, which are inserted through a flanged portion 13 a provided at an outer peripheral portion of the front end side. A shaft insertion hole 19, into which the first to third drive shafts 20, 40, and 50 are inserted, is formed through a substantially central portion of the third pump housing 13 along the axial direction.

A diametrically-enlarged bearing bore portion 19 a is formed at the front end of shaft insertion hole 19 for providing a bearing for the first drive shaft 20. The rear end of the first drive shaft 20 is supported by means of a bearing B9, which is accommodated and held in the bearing bore portion 19 a. Hereupon, the bearing B9 is constructed by a generally-known plane bearing. The bearing B9 is lubricated by working fluid flowing out of the side of the first pump element E1.

On the other hand, a diametrically-enlarged bearing bore portion 19 b is formed at the rear end of shaft insertion hole 19 for providing a bearing for the third drive shaft 50. The rear end of the third drive shaft 50 is supported by means of a bearing B0, which is accommodated and held in the bearing bore portion 19 b. Hereupon, the bearing B0 is constructed by a generally-known ball bearing. The bearing B0 is lubricated by fuel flowing out of the side of the second pump element E2.

The third drive shaft 50 is connected at one end to the first drive shaft 20 through a first joint 51, and also connected at the other end to the second drive shaft 40 through a second joint 52. In the shown embodiment, the first joint 51 and the second joint 52 are constructed by Oldham's shaft couplings that permit a change in the amount of eccentricity among the drive shafts 20, 40, and 50. Concretely, each of these joints is formed into a cylindrical shape. The first joint 51 has a first engagement groove 51 a formed on its one axial end side and serving as a first recessed portion, which is brought into engagement with a width-across-flat portion 20 a corresponding to a protruding portion of the first drive shaft 20, and a second engagement groove 51 b formed on the other axial end side and serving as a second recessed portion, which is brought into engagement with a width-across-flat portion 50 a corresponding to a protruding portion (described later) of the third drive shaft 50. The second joint 52 has a first engagement groove 52 a formed at its one axial end and serving as a first recessed portion, which is brought into engagement with a width-across-flat portion 40 a corresponding to a protruding portion of the second drive shaft 40, and a second engagement groove 52 b formed at the other axial end and serving as a second recessed portion, which is brought into engagement with a width-across-flat portion 50 d corresponding to a protruding portion (described later) of the third drive shaft 50. By virtue of the first engagement grooves 51 a, 52 a and the second engagement grooves 51 b, 52 b, a radial relative movement of each of the drive shafts 20, 40, and 50 to the first and second joints 51, 52 can be permitted. Therefore, a change in the amount of eccentricity between each of the first and second drive shafts 20, 40 and the third drive shaft 50 can be permitted.

By the way, the first and second joints 51, 52 are not limited to the particular embodiment that permits a change in the amount of eccentricity between each of the first and second drive shafts 20, 40 and the third drive shaft 50. In lieu thereof, another type of joint that permits a joining angle change between each of the first and second drive shafts 20, 40 and the third drive shaft 50 may be used. For instance, as a joint that permits a joint angle change, a universal coupling (a universal joint) such as a Cardan joint may be used.

The third drive shaft 50, which is interposed between the first drive shaft 20 and the second drive shaft 40 through the first and second joints 51, 52, has the first width-across-flat portion 50 a, a seal portion (a seal support portion) 50 b, a bearing borne portion 50 c, and the second width-across-flat portion 50 d. The first width-across-flat portion 50 a is located at the front end of the third drive shaft and formed into a flat shape, and provided for coupling with the first joint 51. The seal portion 50 b is located at the intermediate section of the third drive shaft for providing a seal (described later). The bearing borne portion 50 c is located on the rear end side of the seal portion 50 b and formed as a diametrically-enlarged section, and borne or supported by means of the bearing B0. The second width-across-flat portion 50 d is located at the rear end of the third drive shaft and formed into a flat shape, and provided for coupling with the second joint 52. On one hand, the first width-across-flat portion 50 a is kept in fitted-engagement with the second engagement groove 51 b of the first joint 51 on the front end side. On the other hand, the second width-across-flat portion 50 d is kept in fitted-engagement with the second engagement groove 52 b of the second joint 52 on the rear end side.

A pair of seal members S1 and S2 are fitted onto the outer periphery of the seal portion 50 b of the third drive shaft 50, for sealing between the third drive shaft 50 and the shaft insertion hole 19. That is, the first and second seal members S1, S2 are arranged between the first joint 51 and the second joint 52, and more exactly located between the first joint 51 and the bearing B0. The first seal member S1 serves to suppress an inflow of working fluid flowing out of the side of the first pump element E1 into the side of the second pump element E2, whereas the second seal member S2 serves to suppress an inflow of fuel flowing out of the side of the second pump element E2 into the side of the first pump element E1.

A communication passage 53 is formed through the peripheral wall of the third pump housing 13 so as to extend vertically downwards along the radial direction and configured to open into an internal space R defined between the first seal member S1 and the second seal member S2, for intercommunicating the internal space R with the outside. The communication passage 53 is opened to the atmosphere, thereby achieving pressure adjustment between the first and second seal members S1 and S2. The communication passage 53 also serves to discharge working fluid (or fuel), which has flown out of one of pump elements E1, E2 and passed through one of seal members S1, S2, to the outside, thereby suppressing the problem of an undesirable inflow (mixing) of the working fluid (or fuel) into the other of pump elements E1, E2.

The operation and effects characteristic of the pump device of the previously-discussed embodiment are hereunder explained, while comparing with the prior-art pump device.

According to the prior-art pump device, assuming that the first pump element constructs an unbalanced pump element, an eccentric internal pressure is produced by a pumping action of the unbalanced pump element. Therefore, the first drive shaft for driving the first pump element is flexurally deformed from the high-pressure (discharge pressure) side to the low-pressure (suction pressure) side due to the uneven internal pressure. Thus, the first drive shaft becomes deformed eccentrically due to the flexural deformation, and as a result an undesired clearance gap (a radial clearance) is formed or produced between the first drive shaft and a seal member fitted onto the first drive shaft. Accordingly, there is a possibility of an undesirable inflow (mixing) of fluid pertaining to the one pump element side (i.e., the first pump element side) from the one pump element side into the other pump element side by way of the clearance gap.

In contrast to the above, according to the pump device 1 of the previously-discussed embodiment, the first drive shaft 20 and the second drive shaft 40 are connected through the third drive shaft 50. The first and second joints 51, 52 are respectively connected between the corresponding drive shafts (between the first and third drive shafts 20, 50, and between the second and third drive shafts 40, 50), so as to permit a joining angle change or a change in an amount of eccentricity between the corresponding drive shafts. Hence, even when a flexural deformation in the first and second drive shafts 20, 40 has been produced, the flexural deformation can be absorbed by means of the first and second joints 51, 52. As a result, it is possible to suppress the problem of the flexural deformation of one of the first and second drive shafts affecting the other.

In particular, in the shown embodiment, the first pump element E1 constructs a pump element of a variable displacement pump, which is an unbalanced type, and thus it is easy to produce a flexural deformation in the first drive shaft 20. However, with the previously-discussed configuration, there is a merit that it is possible to more effectively suppress the flexural deformation of one of the first and second drive shafts 20, 40 from affecting the other.

Additionally, in the shown embodiment, the discharge port 29 a related to the first pump element E1 is configured to be located above the suction port 28 a in the vertical direction in a vehicle-mounted state. Hence, by virtue of a gravitational force, part of the upward flexural deformation of the first drive shaft 20 can be suppressed (canceled or offset). Accordingly, there is a merit that it is possible to suppress undesirable leakage of working fluid, which may occur owing to a delay in deformation of the seal member S0, whose deformation is induced by the above flexural deformation of the drive shaft.

Additionally, the third drive shaft 50 is supported on the third pump housing 13 by means of the bearing B0. An ability to support the third drive shaft 50 can be improved, thus enabling stable support for the third drive shaft 50. As a result, it is possible to more effectively suppress a flexural deformation of one of the first and second drive shafts 20, 40 from affecting the other.

Furthermore, the first and second joints 51, 52 are provided with respective engagement grooves 51 a, 52 a, serving as first recessed portions, which are brought into engagement with axially opposed ends of the first and second drive shafts 20, 40 (i.e., the width-across-flat portions 20 a, 40 a), respectively. The first and second joints 51, 52 are also provided with respective engagement grooves 51 b, 52 b, serving as second recessed portions, which are brought into engagement with both axial ends of the third drive shaft 50 (i.e., the first and second width-across-flat portions 50 a, 50 d), respectively. In this manner, by virtue of the slider coupling pair 51, 52, a direct misalignment of each of the drive shafts 20, 40, and 50 with respect to the first and second joints 51, 52 can be permitted. Therefore, it is possible to shorten the axial length (the entire length) of each of the drive shafts 20, 40, and 50.

Second Embodiment

FIG. 4 shows the second embodiment of a pump device according to the invention. The second embodiment differs from the first embodiment in that the third drive shaft 50 is supported by means of a pair of bearings. The basic configuration of the second embodiment is similar to the first embodiment, and thus the same reference signs used to designate elements in the first embodiment will be applied to the corresponding elements used in the second embodiment, while detailed description of the same reference signs will be omitted because the above description thereon seems to be self-explanatory (the same will be applied to other embodiments described later).

That is, in a pump device 2 of the second embodiment, both ends of the seal portion 50 b of the third drive shaft 50 are supported by means of a pair of bearings, that is, a first bearing B1 and a second bearing B2. Additionally, the previously-discussed seal member pair, that is, the first seal member S1 and the second seal member S2 are located between the first bearing B1 and the second bearing B2.

Each of the first and second bearings B1, B2 is constructed by a generally-known ball bearing. Each of the first and second ball bearings is comprised of an inner ring fitted to the outer peripheral surface of the third drive shaft 50, an outer ring fitted to the inner peripheral surface of the shaft insertion hole 19 of the third pump housing 13, and a plurality of balls confined between the inner and outer rings. The first bearing B1 is lubricated by working fluid flowing out of the side of the first pump element E1, whereas the second bearing B2 is lubricated by fuel flowing out of the side of the second pump element E2.

Of these bearings B1, B2, the inner ring of the first bearing B1 is press-fitted to the outer peripheral surface of the third drive shaft 50 from the front end side of the third drive shaft 50. The outer ring of the second bearing B2 is press-fitted to the inner peripheral surface of the shaft insertion hole 19 from the rear end side of the third drive shaft 50.

From the above, according to the second embodiment, the third drive shaft 50 is supported by a pair of bearings comprised of the first and second bearings B1, B2. Hence, it is possible to suppress an unintended inclination of the third drive shaft 50. As a result, it is possible to more effectively suppress a flexural deformation of one of the first and second drive shafts 20, 40 from affecting the other.

Additionally, the bearing pair B1, B2 have been located in the third pump housing 13 rather than on the side of first pump housing 11, and thus an ability to support the third drive shaft 50 can be improved. Additionally, it is possible to improve the assemblability of the pump device.

In particular, in the second embodiment, the pump device is configured such that, of these bearings B1, B2, the first bearing B1 is press-fitted from the front end side of the third drive shaft 50, whereas the second bearing B2 is press-fitted from the rear end side of the third drive shaft 50. Hence, this method mounted from both sides is superior in mountability, as compared to a case where both of the bearings B1, B2 have been mounted from only one side of the front and rear ends, thus improving the mountability of each of the bearings B1, B2, and consequently improving the assemblability of the pump device.

Also, in the axial direction of the third drive shaft 50, the first seal member S1 is located between the first bearing B1 and the second bearing B2, whereas the second seal member S1 is located between the first seal member S1 and the second bearing B2. Hence, this configuration enables an increased distance (an increased span) between the bearings B1, B2, as compared to a case where the seal member pair S1, S2 have been located axially outside of the bearing pair B1, B2. This contributes to the improved support stability for the third drive shaft 50.

By virtue of arrangement of the seal member pair S1, S2 located inside of the bearing pair B1, B2, there is a merit that the bearing B1 located on the side of the first pump element E1 can be lubricated by working fluid pertaining to the first pump element E1, whereas the bearing B2 located on the side of the second pump element E2 can be lubricated by fuel pertaining to the second pump element E2.

In a similar manner to the first embodiment, in the second embodiment the internal space R, which is defined between the first and second seal members S1, S2, is opened through the communication passage 53 to the atmosphere, thereby achieving pressure adjustment between the first and second seal members S1 and S2.

Third Embodiment

FIG. 5 shows the third embodiment of a pump device according to the invention. The third embodiment differs from the second embodiment in that the first joint 51 is eliminated and in lieu thereof the first joint is replaced with another connection structure.

That is, in a pump device 3 of the third embodiment, a female spline (internal splines) 20 x is formed and recessed in the rear end of the first drive shaft 20, whereas a male spline (external splines) 50 x is formed on the front end of the third drive shaft 50. By virtue of spline connection of these splines 20 x and 50 x in mesh, these drive shafts 20, 50 are connected to each other such that the first drive shaft 20 and the third drive shaft 50 axially move relatively to one another.

By the way, the connection structure of the first and third drive shafts 20, 50, is not limited to such spline connection. In lieu thereof, for instance, another connection structure in which a hexagonal recess/projection (male/female) fitted-engagement structure may be used.

With the previously-discussed connection structure, the third embodiment can provide the same operation and effects as the second embodiment.

Fourth Embodiment

FIG. 6 shows the fourth embodiment of a pump device according to the invention. The fourth embodiment differs from the third embodiment in that, in a pump device 4 of the fourth embodiment, the second bearing B2, which is constructed by a ball bearing in the third embodiment, is replaced with a second bearing B2 x constructed by a plane bearing.

By virtue of the second bearing B2 x (the plane bearing), the bearing structure can be simplified, thereby improving the assemblability of the pump device, and consequently reducing manufacturing costs.

Fifth Embodiment

FIG. 7 shows the fifth embodiment of a pump device according to the invention. The fifth embodiment differs from the third embodiment in that the second drive shaft 40 and the third drive shaft 50, which are formed separately from each other in the third embodiment, are integrated and therefore the second bearing B2 is eliminated in the fifth embodiment.

That is, in a pump device 5 of the fifth embodiment, the third drive shaft 50 is eliminated and in lieu thereof the front end of the second drive shaft 40 is configured to extend into the shaft insertion hole 19 of the third pump housing 13 and also serves as a seal portion (a seal support portion) 40 b.

The first and second seal members S1, S2 are fitted onto the outer periphery of the seal portion 40 b. The front end of the seal portion 40 b is supported by the bearing B0, which is constructed by a generally-known ball bearing. By the way, in a similar manner to the third embodiment, in the fifth embodiment the bearing B0 can be lubricated by working fluid flowing out of the side of the first pump element E1.

From the above, according to the fifth embodiment, the first pump element E1, which is an unbalanced pump, is easy to produce a flexural deformation in the first drive shaft 20, but the bearing B0 and the seal members S1, S2 are provided on the side of the second drive shaft 40. Thus, it is possible to suppress the flexural deformation of the first drive shaft 20 from affecting the seal members S1, S2.

In particular, the fifth embodiment differs from each of the other embodiments, in that the third drive shaft 50 is not interposed, and therefore there is a merit that it is possible to shorten the entire length of the pump device 5 by an axial length corresponding to couplings (the first and second joints 51, 52) used for connecting the third drive shaft 50. Additionally, it is possible to reduce the number of component parts constructing the pump device 5. This contributes to the improved productivity and reduced manufacturing costs.

While the foregoing is a description of the preferred embodiments carried out the invention, it will be understood that the invention is not limited to the particular embodiments shown and described herein, but that various changes and modifications may be made depending on the specification of an applied system without departing from the scope or spirit of this invention. The inventive concept can be applied to all that can provide the operation and effects as described previously.

In the shown embodiments, the first pump element E1 is exemplified in a variable displacement vane pump element, whereas the second pump element E2 is exemplified in a fixed displacement external gear pump element. It will be appreciated that the pump device according to the invention is not limited to the particular two types of pump elements shown and described herein. It will be understood that all types of pump elements, which are driven by the first and second drive shafts 20, 40, may be included.

As a pump device based on the embodiments described above, for instance, aspects described below can be taken into consideration.

That is, according to one aspect of the invention, a pump device comprises a pump housing having a first pump element housing part and a second pump element housing part formed therein, a first pump element housed in the first pump element housing part and provided for suction and discharge of working fluid, a second pump element housed in the second pump element housing part and provided for suction and discharge of working fluid, a first drive shaft supported on the pump housing for rotationally driving the first pump element, a second drive shaft supported on the pump housing for rotationally driving the second pump element, a third drive shaft supported on the pump housing and located between the first drive shaft and the second drive shaft in an axial direction of the first drive shaft and provided for transmitting a rotational force between the first drive shaft and the second drive shaft, a first joint located between the first drive shaft and the third drive shaft and provided for transmitting a rotational force between the first drive shaft and the third drive shaft and configured to permit a joint angle change or a change in an amount of eccentricity between the first drive shaft and the third drive shaft, and a second joint located between the second drive shaft and the third drive shaft and provided for transmitting a rotational force between the second drive shaft and the third drive shaft and configured to permit a joint angle change or a change in an amount of eccentricity between the second drive shaft and the third drive shaft.

According to a preferred aspect of the pump device, a bearing that supports the third drive shaft is provided.

According to another preferred aspect, in the pump device as recited in any one of preceding aspects, the bearing is constructed by a first bearing located on a side of the first drive shaft in an axial direction of the third drive shaft and a second bearing located nearer to a side of the second drive shaft than the first bearing.

According to a further preferred aspect, in the pump device as recited in any one of preceding aspects, a first seal member is interposed between the first bearing and the second bearing in the axial direction of the third drive shaft, and a second seal member is interposed between the first seal member and the second bearing.

According to a still further preferred aspect, in the pump device as recited in any one of preceding aspects, the pump housing has a communication passage opened at one end into a space defined between the pump housing and the third drive shaft and at the other end outwards, the one end of the communication passage being formed to open between the first seal member and the second seal member in the axial direction of the third drive shaft.

According to another preferred aspect, in the pump device as recited in any one of preceding aspects, the first bearing is a ball bearing having a first inner ring, a first outer ring, and a plurality of balls confined between the first inner ring and the first outer ring, the second bearing is a ball bearing having a second inner ring, a second outer ring, and a plurality of balls confined between the second inner ring and the second outer ring, an inner periphery of the first inner ring is press-fitted to an outer peripheral surface of the third drive shaft, and an outer periphery of the second outer ring is press-fitted to an inner peripheral surface of the pump housing.

According to another preferred aspect, in the pump device as recited in any one of preceding aspects, the first pump element is provided with a rotor housed in the first pump element housing part and rotationally driven by the first drive shaft, a plurality of vanes retractably accommodated in respective slots formed and cut in the rotor, and an annular cam ring located in the first pump element housing part such that the cam ring can be displaced eccentrically to an axis of the first drive shaft and configured to define a plurality of pump chambers in conjunction with the rotor and the plurality of vanes, wherein the cam ring is driven and controlled by a control means configured to control internal pressures in a first fluid-pressure chamber and a second fluid-pressure chamber, whose chambers are defined between the first pump element housing part and the cam ring and formed to oppose each other on opposite sides of the cam ring.

According to another preferred aspect, in the pump device as recited in any one of preceding aspects, the pump housing is formed of a first pump housing having a cylindrical section formed on an outer peripheral side of the first drive shaft and configured to accommodate the first pump element and a bottom section provided at one axial end of the cylindrical section, the one axial end being opposite to the second drive shaft, and a third pump housing located on a side of the second drive shaft in an axial direction of the cylindrical section and configured to accommodate the third drive shaft, and the third drive shaft is supported by a pair of bearings located in the third pump housing.

According to another preferred aspect, in the pump device as recited in any one of preceding aspects, one of the pair of bearings is inserted from one end of the third pump housing and the other of the pair of bearings is inserted from the other end of the third pump housing in the axial direction of the third drive shaft.

According to another preferred aspect, in the pump device as recited in any one of preceding aspects, a discharge port, which is configured to open into a region such that a volume of each of the pump chambers decreases with rotation of the rotor, is located above a suction port, which is configured to open into a region such that the volume of each of the pump chambers increases with rotation of the rotor, in a vertical direction in a vehicle-mounted state.

According to another preferred aspect, in the pump device as recited in any one of preceding aspects, the first joint has a first recessed portion which engages a protruding portion provided at one of opposing ends of the first drive shaft and the third drive shaft and a second recessed portion which engages a protruding portion provided at the other of the opposing ends of the first drive shaft and the third drive shaft, and the second joint has a first recessed portion which engages a protruding portion provided at one of opposing ends of the second drive shaft and the third drive shaft and a second recessed portion which engages a protruding portion provided at the other of the opposing ends of the second drive shaft and the third drive shaft.

According to a further preferred aspect, in the pump device as recited in any one of preceding aspects, the pump device comprises a pump housing having a first pump element housing part and a second pump element housing part formed therein, a first pump element housed in the first pump element housing part and provided for suction and discharge of working fluid, a second pump element housed in the second pump element housing part and provided for suction and discharge of working fluid, a first drive shaft supported on the pump housing for rotationally driving the first pump element, a second drive shaft supported on the pump housing for rotationally driving the second pump element, a joint located between the first drive shaft and the second drive shaft and provided for transmitting a rotational force between the first drive shaft and the second drive shaft and configured to permit a joint angle change or a change in an amount of eccentricity between the first drive shaft and the second drive shaft, a bearing provided between the joint and the second pump element in an axial direction of the second drive shaft for supporting the second drive shaft, and a pair of seal members provided between the bearing and the second pump element in the axial direction of the second drive shaft, wherein the first pump element is provided with a rotor housed in the first pump element housing part and rotationally driven by the first drive shaft, a plurality of vanes retractably accommodated in respective slots formed and cut in the rotor, and an annular cam ring located in the first pump element housing part such that the cam ring can be displaced eccentrically to an axis of the first drive shaft and configured to define a plurality of pump chambers in conjunction with the rotor and the plurality of vanes. 

1. A pump device comprising: a pump housing having a first pump element housing part and a second pump element housing part formed therein; a first pump element housed in the first pump element housing part and provided for suction and discharge of working fluid; a second pump element housed in the second pump element housing part and provided for suction and discharge of working fluid; a first drive shaft supported on the pump housing for rotationally driving the first pump element; a second drive shaft supported on the pump housing for rotationally driving the second pump element; a third drive shaft supported on the pump housing and located between the first drive shaft and the second drive shaft in an axial direction of the first drive shaft and provided for transmitting a rotational force between the first drive shaft and the second drive shaft; a first joint located between the first drive shaft and the third drive shaft and provided for transmitting a rotational force between the first drive shaft and the third drive shaft and configured to permit a joint angle change or a change in an amount of eccentricity between the first drive shaft and the third drive shaft; and a second joint located between the second drive shaft and the third drive shaft and provided for transmitting a rotational force between the second drive shaft and the third drive shaft and configured to permit a joint angle change or a change in an amount of eccentricity between the second drive shaft and the third drive shaft.
 2. A pump device as recited in claim 1, wherein: a bearing that supports the third drive shaft is provided.
 3. A pump device as recited in claim 2, wherein: the bearing is constructed by a first bearing located on a side of the first drive shaft in an axial direction of the third drive shaft and a second bearing located nearer to a side of the second drive shaft than the first bearing.
 4. A pump device as recited in claim 3, wherein: a first seal member is interposed between the first bearing and the second bearing in the axial direction of the third drive shaft, and a second seal member is interposed between the first seal member and the second bearing.
 5. A pump device as recited in claim 4, wherein: the pump housing has a communication passage opened at one end into a space defined between the pump housing and the third drive shaft and at the other end outwards, the one end of the communication passage being formed to open between the first seal member and the second seal member in the axial direction of the third drive shaft.
 6. A pump device as recited in claim 3, wherein: the first bearing is a ball bearing having a first inner ring, a first outer ring, and a plurality of balls confined between the first inner ring and the first outer ring; the second bearing is a ball bearing having a second inner ring, a second outer ring, and a plurality of balls confined between the second inner ring and the second outer ring; an inner periphery of the first inner ring is press-fitted to an outer peripheral surface of the third drive shaft; and an outer periphery of the second outer ring is press-fitted to an inner peripheral surface of the pump housing.
 7. A pump device as recited in claim 1, wherein: the first pump element comprises: a rotor housed in the first pump element housing part and rotationally driven by the first drive shaft; a plurality of vanes retractably accommodated in respective slots formed and cut in the rotor; and an annular cam ring located in the first pump element housing part such that the cam ring can be displaced eccentrically to an axis of the first drive shaft and configured to define a plurality of pump chambers in conjunction with the rotor and the plurality of vanes, wherein the cam ring is driven and controlled by a control means configured to control internal pressures in a first fluid-pressure chamber and a second fluid-pressure chamber, whose chambers are defined between the first pump element housing part and the cam ring and formed to oppose each other on opposite sides of the cam ring.
 8. A pump device as recited in claim 7, wherein: the pump housing comprises: a first pump housing having a cylindrical section formed on an outer peripheral side of the first drive shaft and configured to accommodate the first pump element and a bottom section provided at one axial end of the cylindrical section, the one axial end being opposite to the second drive shaft; and a third pump housing located on a side of the second drive shaft in an axial direction of the cylindrical section and configured to accommodate the third drive shaft, wherein the third drive shaft is supported by a pair of bearings located in the third pump housing.
 9. A pump device as recited in claim 8, wherein: one of the pair of bearings is inserted from one end of the third pump housing and the other of the pair of bearings is inserted from the other end of the third pump housing in the axial direction of the third drive shaft.
 10. A pump device as recited in claim 7, wherein: a discharge port, which is configured to open into a region such that a volume of each of the pump chambers decreases with rotation of the rotor, is located above a suction port, which is configured to open into a region such that the volume of each of the pump chambers increases with rotation of the rotor, in a vertical direction in a vehicle-mounted state.
 11. A pump device as recited in claim 1, wherein: the first joint has a first recessed portion which engages a protruding portion provided at one of opposing ends of the first drive shaft and the third drive shaft and a second recessed portion which engages a protruding portion provided at the other of the opposing ends of the first drive shaft and the third drive shaft; and the second joint has a first recessed portion which engages a protruding portion provided at one of opposing ends of the second drive shaft and the third drive shaft and a second recessed portion which engages a protruding portion provided at the other of the opposing ends of the second drive shaft and the third drive shaft.
 12. A pump device comprising: a pump housing having a first pump element housing part and a second pump element housing part formed therein; a first pump element housed in the first pump element housing part and provided for suction and discharge of working fluid; a second pump element housed in the second pump element housing part and provided for suction and discharge of working fluid; a first drive shaft supported on the pump housing for rotationally driving the first pump element; a second drive shaft supported on the pump housing for rotationally driving the second pump element; a joint located between the first drive shaft and the second drive shaft and provided for transmitting a rotational force between the first drive shaft and the second drive shaft and configured to permit a joint angle change or a change in an amount of eccentricity between the first drive shaft and the second drive shaft; a bearing provided between the joint and the second pump element in an axial direction of the second drive shaft for supporting the second drive shaft; and a pair of seal members provided between the bearing and the second pump element in the axial direction of the second drive shaft, wherein the first pump element comprises: a rotor housed in the first pump element housing part and rotationally driven by the first drive shaft; a plurality of vanes retractably accommodated in respective slots formed and cut in the rotor; and an annular cam ring located in the first pump element housing part such that the cam ring can be displaced eccentrically to an axis of the first drive shaft and configured to define a plurality of pump chambers in conjunction with the rotor and the plurality of vanes. 